Other such disputes stem from lines drawn in the sands by imperial mapmakers: Iraq and Kuwait; the United Arab Emirates and Iran; Saudi Arabia and Yemen. Saudi Arabia, however, has also agreed a border with Oman, along the old colonial boundary.
The incident with Qatar is different in two main respects, and therefore all the more puzzling. There was no apparent political reason to blow up an incident at this time. Saudi Arabia and Qatar had fought side by side against Iraq in the Gulf war. They are joined in the Gulf Co-operation Council. Qatar is dwarfed by the much larger and richer Saudi Arabia. And the border between them had not been hitherto been in dispute, although the 1965 agreement over its delineation was never formally ratified.
Wednesday night's fracas occurred when bedouin strayed from Saudi Arabia into Qatar. Most bedouin have scant regard for international boundaries dividing historic grazing lands. The Qataris, however, said that these had pulled down the Qatari flag and smashed up a border post. Two members of the Qatari defence forces were killed.
The incident has led to a diplomatic row. Qatar reacted vehemently, suspending the 1965 border agreement. The Saudis responded by declaring this an unacceptable unilateral action.
The seeds of the dispute lie in the fact that the border does a V, and appears to pass through UAE territory. In 1990, it emerged the UAE had, in 1974, ceded some land to the Saudis; now the road between it and Qatar runs through Saudi land. Qatar accuses the Saudis of unilaterally demarcating the border and preventing the passage of trucks unless they pass through Saudi territory.